Ugandan police appear to be making progress in the wrongful death investigation of reality show producer Jeff Rice.

Deputy police spokesperson Judith Nababooka confirms to E! News that police have arrested and detained a suspect they believe assisted former Amazing Race freelance producer Rice and production assistant Kathryne Fuller with buying the illicit drugs that left Rice dead and Fuller in critical condition Tuesday in Kampala City.

Although Nababooka declined to reveal the suspect's name due to the ongoing investigation, a police source tells E! News the man who was arrested and detained at Central Police Station in Kampala is Moses Kalanzi, a 23-year-old special hire driver.

According to the source, "there was constant communication between the special hire driver and Rice on phone about the purchase of the drugs. So we want to know the source of the drugs and how it is trafficked into the country. He has recorded a statement and investigations are ongoing."

In a press conference, Brad Nathanson, a private investigator and friend of the producer who was there to pick up Rice's body along with family members, put forward a theory about what killed Rice: "I carried out my own investigation. There is no foul play but these two consenting adults looked for drugs but they bought bad cocaine. What they bought was just rubbish."

Police sources stress that importation, supply and consumption of cocaine without authorization is illegal in Uganda, while noting that drug trafficking in Uganda is on the increase. Just last year, police reportedly destroyed $14 billion worth of illicit drugs trafficked in the country mostly through Entebbe International Airport.

As for how Fuller, who was found alongside Rice, is doing, a Uganda police source tells E! that while Fuller is still hospitalized at Surgery Clinic in Kololo, a Kampala suburb, and is paralyzed on the right side, she can now talk.

However, according to clinic officials, Fuller isn't talking much and has even declined to speak with her own father, Stuart Fuller, who is residing at Kampala Serena, the same hotel where Fuller and Rice were staying.

At a press conference he described his mood: "I am stressed, disappointed, sad. What can you say as a father, what do you do when you have raised your child to the best of energy. I am her father. I will support her until the police will let her go."